intel/brw: Fix DEBUG_OPTIMIZER

Due to recent regression, adding INTEL_DEBUG=optimizer is dumping
shader optimization pass details to console rather than to respective
files.
Thank you, Kenneth W Graunke for helping me figure this out.

Fixes: 17b7e49089 ("intel/brw: Move out of fs_visitor and rename print instructions")

Signed-off-by: Sushma Venkatesh Reddy <sushma.venkatesh.reddy@intel.com>
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30389>

src/intel/compiler/brw_fs.cpp

@@ -1554,7 +1554,7 @@ fs_visitor::debug_optimizer(const nir_shader *nir,
                       iteration, pass_num, pass_name);
    if (ret == -1)
       return;
-   brw_print_instructions(*this);
+   brw_print_instructions(*this, filename);
    free(filename);
 }